Wrong guys! And here's one of many counter examples.
This guy got into Smash as a trophy, was only in one game, AND it was Japan only. And there are many other characters in Smash who fall into this category, who've either been trophied or made into a playable character, like the Ice Climbers who were only relevant once in history.
If 1st, 2nd and other 3rd party characters that do that can get in as trophies or playable characters, it's not insane at all to think more popular 3rd party characters, who have starred in multiple titles AND are close to Nintendo, can get in as trophies, or have a shot at being a playable character.
This guy got into Smash as a trophy, was only in one game, AND it was Japan only. And there are many other characters in Smash who fall into this category, who've either been trophied or made into a playable character, like the Ice Climbers who were only relevant once in history.
If 1st, 2nd and other 3rd party characters that do that can get in as trophies or playable characters, it's not insane at all to think more popular 3rd party characters, who have starred in multiple titles AND are close to Nintendo, can get in as trophies, or have a shot at being a playable character.